Synonyms: leishmaniosis, kala azar, oriental sore

What is it?

Leishmaniasis is caused by different species of the protozoan genus Leishmania. This parasite is transmitted by the sandfly (phlebotoma), a tiny fly that is abundant in warm, dry and arid environments.  Leishmaniasis can be either transmitted only between sandflies and humans or it can be zoonotic, involving an animal reservoir.  The discussion below is limited to zoonotic leishmaniasis. Many mammalian species are receptive but only humans and dogs develop the disease. The types of disease caused by Leishmania species can be roughly grouped into the (muco-)cutaneous form and the visceral form. In Africa, the zoonotic cutaneous form is mostly caused by Leishmania major and, to a lesser extent, by Leishmania aethiopica in Ethiopia, Sudan and Kenya, and by an unidentified species of leishmania in Namibia. Some species of rodents (a type of gerbil, known as a jird) have been shown to act as reservoir of L. major whereas hyraxes are a  reservoir of Leishmania aethiopica.[1] The zoonotic visceral form is mostly caused by Leishmania infantum. In Africa, the Sahel and the Maghreb regions are the most affected areas. Dogs act as a reservoir of L. infantum.

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Leishmania

Leishmaniasis WHO factsheet (English only)

Sandfly

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Life cycle (2'17; no language with Spanish writings)

New drug tested on leishmaniasis in India and relevant for dogs (6'01; English)

Patient Education Institute (3'44; English)

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Merck Manual (English only)

Resources for health professionals: leishmaniasis, CDC (English only)

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Lecture by a professor of Yale University (13'; English)

Leishamania donovani (5'5; English)

Tutorial on leishmaniasis (10'52; English)

How to recognize it

In humans, cutaneous leishmaniasis presents as ulcers of the skin, mouth or nose. Whereas cutaneous leishmaniasis is usually self-healing, it may have severe social impacts on infected people, especially if the lesions are in the face. Visceral leishmaniasis is also called Kala-Azar. It is a very debilitating and lethal disease affecting the liver, the spleen and bone marrow, mainly in children and immunosuppressed patients in endemic areas. Kala-azar usually starts with a cutaneous ulcer. Infected liver and spleen inflate and cause a swollen abdomen. Other symptoms, including fever, are not very specific and might be confused with malaria. Deterioration of the immune system is frequently observed.

Microscopy is used to confirm the presence of the parasite in biopsies. Serological tests are used to confirm visceral leishmaniasis.

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Resources for health professionals: leishmaniasis, CDC (English only)

WHO: Leishmaniasis in humans (p20; English)

WHO: diagnosis (p64; English)

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Development of a diagnostic test (2'01; English)

Leishamania donovani (5'5; English)

Tutorial on leishmaniasis (10'52; English)

Dogs also present ulcerative cutaneous lesions in the cutaneous form. The visceral form is often accompanied with skin lesions (excessive epidermal scaling, hair loss and abnormally long or brittle nails) and general symptoms (fever and loss of appetite and weight).  However, many infected dogs show no symptoms at all, especially dogs of indigenous breeds living in endemic areas.

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OIE Terrestrial manual

Phlebotomine Sandflies (genus Phlebotoma) are tiny insects which resemble mosquitoes but are much smaller, measuring about 3 mm in length. They take their blood meals at night. They are silent but their bites are painful.

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Animation for CDC trap (38''; no language)

WHO: Sand flies

How to control it

Leishmaniasis is closely associated with the abundance of sandflies. These flies are adapted to develop in warm and arid environments. They lay eggs in wall cracks and constructions where the conditions are sufficiently humid to allow the development of the larval stage. Prevention should therefore aim at improving the sanitation in villages and municipalities. Chronically infected animals and humans are infective to sandflies. As a consequence, dog, gerbil and hyrax populations might need to be controlled in areas at risk. However, abundant vector and reservoir hosts assure early infection of infants, who will develop a specific immunity against the parasite. Disrupting this equilibrium (endemic stability) might cause more clinical cases among older age classes. Rodents can be controlled using rodenticides. Climate change might affect the geographical distribution of the vector. Mathematical and geographic models can be used to predict suitable habitats for sandflies.

General considerations on dog management

In Africa, most stray dogs are associated with a human community that provides them with food. Some apparently stray dogs are actually owned, but left to roam freely. Some stray dogs return to the wild (feral dogs) but struggle to reproduce. As a consequence, most feral dogs come from owned or stray dog populations. Controlling births among owned and stray dog populations would, therefore, have an impact on all dog populations, including feral dogs.

Unfortunately, no easy and cheap contraceptive methods are available. Castration of males is not useful because one single male can fertilize many females. Spaying female dogs is recommended but more difficult to implement. Alternatively, euthanasia of pups could be recommended but this should be done in a humane way, probably requiring veterinary expertise.

Killing dogs has been demonstrated to be counterproductive in several situations, because the killed stray and feral dogs are quickly replaced by new dogs from outside the community, with the attendant risk of bringing in diseases (e.g. rabies). The dog capture, sterilization, vaccination, treatment and release method is recommended but, again, is very demanding for veterinary services.

Finally, stray dogs mostly feed on waste. Improved waste management is likely to result in reduced stray dog populations.

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Guidelines from World Society for the Protection of Animals (English only)

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Estudio demografico sobre la tenencia responsable de mascotas y prevencion de la hidatidosis (Chilean video) (4'41; Spanish)

FAO film on rabies control (21'00; English only)

Rabies control in Liberia (4'18; English only)

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OIE terrestrial manual code (English only)

WHO guidelines for dog management (1990; English only)

WHO report on echinococcosis control (English only)

Leishmaniasis is not contagious. It can only be transmitted by sandflies. Consequently, sandflies play a pivotal role in prevention. The following prevention methods are advised in Africa:

• Sandflies are more abundant in squalid environments: people and animals should avoid such places at night
• Use of mosquito nets and screens: sandflies are so small that they can usually cross them
• Insecticides applied on the walls or animals may reduce the sandfly abundance
• Repellents can be used to reduce the risk of bite
• Improved sanitation should reduce the abundance of the larval stage of sandflies in the environment
• Potential reservoir hosts (dogs and gerbil rodents) could be controlled
• No vaccines are available for use in humans; a vaccine was developed against European leishmaniasis in dogs

Repellents and insecticides may be used on dogs. Repellents present the advantage of protecting dogs against infective bites, unlike insecticides. The danger might be that sandflies then prefer feeding on human beings. Unless they have a repellent activity, the use of insecticides on dogs might not protect them against leishmaniasis because the sandfly needs to bite the dog to come into contact with the insecticide. However, insecticides used on dogs should reduce the risk of transmission to other animals and human beings and reduce the sandfly abundance.

Several drugs are available to treat cutaneous and visceral leishmaniasis in humans and dogs. Unfortunately, treatments are demanding (long, toxic and expensive) and prone to resistance. Early diagnosis and early treatment are keys for successful therapies. Detection and monitoring of therapeutic failures is critical to identify suspicions of drug resistance.

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Canileish Leaflet (Dog vaccination; English)

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Control of canine leishmaniasis (10'52; English)

Leishmaniasis in dogs (5'54; Spanish)

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Canileish, dog vaccine (English - PDF available in all EU languages)

Control in dogs (p91; English)

Control of rodents (p92; English)

Control strategies (p122; English)

Treatment and vaccine in humans (p54; English)

Vector control (p94; English)

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Advocacy for early chemotherapy (6'00; English)

Leishamania donovani (5'5; English)

Tutorial on leishmaniasis (10'52; English)

Cultural and geographical specificities

In Africa, zoonotic visceral and cutaneous leishmaniasis mostly affects populations in northern Africa and the Sahel region whereas sporadic zoonotic cutaneous leishmaniasis occurs especially in the highland areas of Ethiopia and other locations in East Africa as well as Namibia.

Pastoralist communities

Pastoralists are exposed to both visceral and cutaneous forms.  Recommendations are:

• Detect and promptly report leishmaniasis cases in dogs and humans
• Identify sandfly infested areas and avoid them, particularly at night
• Protect yourself against sandflies (mosquito nets and screens are not always effective because of the small size of sandflies)
• Keep dogs away from sandfly infested areas
• Use insecticides on dogs to reduce the sandfly population and the transmission to humans or other dogs (e.g.: baths, collars, pour-ons)
• Euthanize dogs suffering from leishmaniasis, on public health and humane grounds
• Identify, avoid or control gerbils and hyraxes in endemic areas as they can act as a reservoir of L. major and L. aethiopica, respectively

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Leishmaniasis, WHO: Ethiopia (English and Spanish)

Communities in northern Africa and the Sahel region

Both visceral and cutaneous forms are found in these regions, although visceral is limited to northern Africa. Recommended extension messages are:

• Detect and promptly report leishmaniasis cases in dogs and humans
• Identify sandfly infested areas and avoid them, particularly at night
• Protect yourself against sandflies (mosquito nets and screens are not always effective because of the small size of sandflies)
• Keep dogs away from sandfly infested areas
• Use insecticides on dogs to reduce the sandfly population and the transmission to humans or other dogs (e.g.: baths, collars, pour-ons)
• Euthanize dogs suffering from leishmaniasis, on public health and humane grounds
• Identify, avoid or control gerbil rodents in endemic areas as they can act as a reservoir of L. major

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Leishmaniasis in Morocco (French only)

Mixed farming communities in more humid regions

In areas were endemic or sporadic cutaneous leishmaniasis occurs

• Detect and promptly report leishmaniasis cases in and humans
• Identify sandfly infested areas and avoid them, particularly at night
• Protect yourself against sandflies (mosquito nets and screens are not always effective because of the small size of sandflies)
• Identify, avoid or control hyraxes in endemic areas as they can act as a reservoir of L. aethiopia

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